Pickup Technology

The pickup is one of the most important chain in a analogue set-up since it is the device that actually converts information contained in the grooves of a record to an electric signal(it is in other words a transducer). Most high quality types are Moving Coil (MC) where the coil assembly is fixed on the end of the cantilever thereby making the user replacement of the stylus near impossible, most budget types however are Moving Magnet (MM) whereby the coils are fixed in the cartridge body but the magnet is on the cantilever, this simplifies the stylus/cantilever assembly greatly and means that in almost all cases the stylus is user replaceable. Other variants like Piezoelectric or Moving Iron (MI) are also to be found, although rare in new equipment.

The Moving Coil type is by far the most common type of a high quality pickup, the mechanical energy is converted into electrical energy by using a wound copper coil which is fastened to the end of the cantilever, on the opposite end to the stylus, while a magnet is fastened into the housing or frame of the pickup itself. This system has a number of advantages, it has a low moving mass, has a high structural integrity since the unit is usually a whole with the stylus/cantilever not being user replaceable. There were some MC designs made in Japan in the late 70's and early 80's that had user replaceable stylus assemblies but they are rare enough these days to be immaterial. There are plenty of specialised concerns making and servicing them meaning that there is a bewildering array of specialist variants and services available for MC designs. The disadvantages are they are more expensive to make since it's much more difficult to construct the coil piece on the end of the cantilever that it is to build it into the pickup housing, for the same reason it's more complicated to automate the manufacture of them and thus there are few worth while low end designs, the very best MC pickup usually have a low or very low output since they have fewer windings on the coil to minimise the mass on the cantilever, but this puts strains on the amplification requiring much more gain than what you can expect with a similar MM design, amplifying those signals has become something of a black art and the how's and the whatnots are endlessly debated on, the lack of user replaceable stylii means that they have to be sent to the manufacturer or a specialised service company when it gets worn out and so on. There are variants on the theme, silver is occasionally used in the coil windings to gain more efficiency, and in Asia gold is also popular but in general that is frowned upon in the West although the softer gold wire actually makes for more precise winding and gold is chemically more stable, platinium is also an exellent choise to coil winding, possibly the best material availabe but very difficult to source and either material is typically only on expensive variants, better coil winding robots have meant reasonably priced high output designs are slowly becoming more commonplace. The moving coil pickup was developed by the Danish company Fonofilm Industri (now Ortofon) in the late thirties/early 40's as a cutterhead which was turned into a commercial pickup in 1948 (which is still available BTW as the Ortofon Mono 63) with a stereo variant appearing in the 50's as the SPU, all current true MC designs are direct or indirect descendants of those pickups. The large support industry for MC designs has meant that old designs can be kept going almost endlessly, cantilevers and stylii can be replaced and coils repaired although there are a few exceptions where something specialised like a ruby cantelever has to be replaced with a more generic part.

The Moving Magnet can be seen as the inverse of a MC with the magnet being mounted on the end of the cantilever while the coil is fixed into the pickup housing. This is the most common type of pickup made today and has a number of advantages such as it's much simpler to mass manufacture than an MC, is very linear, since the cantilever construction is very simple the use of a replaceable stylus is made possible, it's very effective (Sensitive) compared to a MC and most amplifiers come with inputs intended for use directly with an MM pickup. The disadvantages are that it's slightly less accurate than an MC due to a higher moving mass, the (almost universal) use of a replaceable stylus means that the pickup housing is less rigid, it's has a tendency to distort on records that have high modulation levels such as 45's and 12's dance records, the high end response has a tendency to be slightly damped and the general perception that they are inferior to MC's means that there are very few specialised concerns making high end models these day's meaning that it's almost impossible to find a MM with a modern line contact stylus and better cantilever materials which means that in practice, as opposed to theory, they do not track as well as high end MC designs and finally there are very few if any persons out there there that specialise in repairing them, making older models more vulnerable to the ravages of age. The MM has been with us since the 1910's at the least although in the form that we know it today it's based on a design that was patented by ELAC in 1957 (the later USA patent was issued to Shure Inc. but is just a copy of the ELAC one). Note that in old ads for pickups MM carts are sometimes called "Induced Magnet", "Moving Armature", "Induced Flux" or "Variable Reluctance", not all of those descriptions are technically correct BTW.

The Ribbon pickup was popular in the 50's as a high end device, technically it's best described as a 2D variant of the moving coil principle although the basic idea behind it is similar to a variant of the ribbon loudspeaker principle, but the coil is wound onto a sort on an U frame connected to the cantilever with a magnet fastened to the pickup housing, this type of design was mostly seen in the UK, since the ribbon pickup is only useable for Mono pickups it disappeared in the stereo age.

The Moving Iron is basically a moving coil pickup with iron in the coil, this makes it more effective as a generator (ie you get a higher output voltage) but they do not appear to sound as good as similar MC designs. There are quite a few variants of the principle, some of them designed more like a MM pickup with the coil partially in the housing, the main problem with any sort of MI design is the presence of iron, the pole pieces end up rusting and even falling off, the actual lifetime differs from manufacturer to manufacturer. The best known MI basic design is the one that Grado patented in 1957 or thereabouts but most modern devices owe nothing to that patent except in name.

The Piezoelectric pickup takes advantage of the fact that certain crystal structures generate electricity when put under mechanical stress, this system is remarkably efficient, in fact so much so that a crystal pickup can generate enough voltage to drive a line input directly and is very cheap to manufacture but has problems with linearity, the RIAA pre compensation Eq. is designed to accommodate the characteristics of this sort of transducer. Almost all early piezoelectric pickups were made out of crystals grown in Rochelle Salts solution and were almost all budget devices although in the 50's and early 60's there were a few designs that attempted to gain higher quality, in some cases there was a noticeable improvement in linearity but that created a problem with the pre compensation and in those cases you will often find resistor networks inside the pickup that modify the signal back to that of a normal crystal pickup. As for old crystal pickups, these can be repaired or rebuilt but the crystal element deteriorates over time so even if you find a NOS unit chances are that you cannot use it without a rebuild or that the performance will be abysmal, thankfully however most carts of this type are still being made (or equivalents). In the 60's ceramic pickups started to replace the crystal pickups in the marketplace, they have the exact same characteristics as the ones made out of Rocelle salts but are easier to assemble and last much longer, longer than either MM or MC's in fact and in the 70's ceramic designs appeared that competed with other high end pickups in quality. Piezoelectric pickups are sometimes seen referred to as "Electrets" and the first company to design crystal pickups was Brush Development Company in the 1910's although they never actually made them themselves commercially but rather licensed the concept and the first models appear to have turned up for sale in the 1930's.

The Optical pickup pops up from time to time, it's basically a photocell that senses the movement of the cantilever and thus acts as a transducer, in theory should sound great and have a long livetime but in practice neither objective was really archived. First seen commercially in the early 40's on Philco equipment but the best models were made by Yamaha Corp. in the 70's and cost as much as a high end MC pickup.

The Electrostatic pickup is yet another obscure device from the 50's that died out with the mono age since it is difficult to fabricate in 3D, they did not require an energiser (i.e. they were self energising like a Koss Electrostatic headphone)

The Digital Pickups are almost unheard of as commercial devices (one made today at a price of around 15k €) but do crop up from time to time, in them the movement of the cantilever is digitised directly in the pickup and transferred to an audio system as digital data. The reason that they are not more commonplace is the price and the need for computing power, the overhead of just the RIAA pre compensation calculation does reqire at the least a 40 bit headroom to sound reasonable and preferably 56 bits or higher with a 16 bit 44KHz signal but that means that it will probably not work in real time on a 32 bit computer (i.e. a common PC) unless there is a trade-off somewhere and with a higher sampling or bitrate the problems mount, and that is without counting in all the other calculations needed, all of this computing can be accomplished in the analogue world with a 20p op-amp (most people think Eq. is cheap and easy to do digitally but that depends on what sort of Eq. that is and to what spec.).

Pickup Mounting Systems


The way a pickup is mounted into a tonearm may seem like a given thing or an irrelevant subject, however the mounting system may influence how a well a record player functions since it governs how well the pickup and the arm mate together, both in a straight mechanical sense in how well the stylus is aligned to the groove and as is how tight the 2 mate but that affect the self-resonance of the arm and hence the sound quality. By far the most common arrangement of fastening the pickup to the tonearm of a home audio system is the 1/2 inch mount and the most common type in broadcast or DJ systems is the Ortofon mount.

Standard/Half Inch Mount

By far the most common mounting arrangement is simply called a standard mount or in English speaking countries a half inch mount (or 12,7mm for the rest of the universe that has no clue as to what an inch is), but in that case 2 holes are on both the pickup and the tonarm headshell spaced half an inch apart and you fasten the two together by using non magnetic bolts, this is simple, effective and extremely cheap solution but not optimal, in search of improved mechanical integrity some pickup manufacturers have started to use threaded holes in the last few years, in the case of cheaper models the threads are drilled into the pickup but in the more expensive variants a resin is poured into the holes with a bolt in place, correctly done this makes for more accurate threading.

Linn Mount
A standard mount is fine for spherical stylii but when it comes to pickups with a line contact stylus things can get a bit trickier since the working part of the stylus is so thin you will have to be very exact with the alignment of the pickup relative to the groove. This has given birth to the Linn Mount which simply adds a third hole on the front, this makes the cart easier to align and should improve mechanical integrity a bit but also maintains compatibility with standard mount, but that is its main benefit.

T4P or P Mount
T4P is the correct name for what is called a "P mount" in the English speaking world, it's is a mounting system mostly found in cheap record players whereby the cartridge is fastened directly to the end of the tonearm with a single bolt and there is no headshell as such, this is a faster and more accurate method than the more common arrangement and thus cheaper but is less flexible, this is mostly seen used in turntables that feature unadjustable arm arrangements in which case it's use is fully justified, but was popular for a while in mid price Japanese turntables but is thankfully getting rarer, there are still plenty of replacement carts available for this configuration including MM variants from Audio Technica and Ortofon in addition to one MC model from the latter company, if the arm does however not have adjustable counterweight and anti-skating you will have to limit your purchase to something with a very similar mechanical specifications to the original pickup..

Ortofon connector
The Ortofon connector which you will also see referred to as a SME connector is actually a connection between a headshell and a tonearm, the removable headshell is usually a replacement for a normal one and features a half inch mount but there is a number of pickups available that are built straight into a headshell and are not meant to be removed from there, having the headshell detachable from the rest of the arm is necessary for professional turntables since you will have to be able to switch pickups quickly in case of failure, this arrangement also allows companies to get more out their investment in specialised pickups such as Mono units as they become easily transportable between record decks thus all DJ and broadcast turntables feature this configuration but also is popular amongst Japanese and other Asian audiophiles where they often have a collection of pickups to "suit each musical genre" etc. Note that the electrical connections are to the headshell in this case and there is a number of older tonarms and pickups that are only wired up for mono and only feature 2 connecting pins. There is a number of similar headshell connectors that are merely historical curios now.

Stylus variations


Elliptical Stylii
This is really the first line contact profile stylus but was originally designed as a way to allow users of electric pickups to use one diamond stylus rather than a collection of them, but the wildy different cutting profiles used up unthil the 1950's meant that you typically had to have at the least 2 or three for optimal use of your record collection. An elliptical profile (also know as oval profile) meant that regardless of the shape of the groove the stylus got almost as much on axis contact with the groove as a stylus specially cut for that groove type and usually got much less off axis contact, it was in other words not just almost as good as specially cut stylii but often better. It is not entirly clear who invented the elliptical, but it appears to have been introduced in the Soviet Union in the 1930's and made it to the USA in the 40's, there had been earlier attemps at a line contact stylii earliest patent we have found is from 1907 but the modern elliptical is really the firts practical one. There was a lot of resitance to the idea initially since in the 1910's exstencive testing had shown a conical stylus got a better contact with a steel stylus and that became dogma even though the case was different with harder materials.

The main disadvantage of the elliptical shape is simply the extra cost of hand polishing it and this kept it confined to the more expencive pickups and the aftermarket until the 1970's, when a certain European manufacturer of spherically polished industrial quality diamonds intended for use in watch movements designed a revolutionary new automatic polishing machine that was meant to make sperical shaped diamonds but due to design fault spat out elliptical ones at an alarming rate. After it was pointed out to the gent who owned the machine that this could be a selling point rather than a disaster we started to see mid priced pickups featuing this stylus shape and by the time the 90's were upon us some budget models started to feature them. Today there is no real price difference between the raw price for an industrial quality elliptical and shperical stylus, the only thing is that it is slightly more diffucult to mount an elliptical by hand than a sperical due to the alignment needed, but even that has been overcome and Ortofon uses elliptical stylii in all of their budget bodel including the cheapest ((OEM)) models..

Flipover stylus
Also commonly referred to as a turnover stylus it's is actually something of a misnomer since you do not flip the stylus over but the cantelever. The flipover is simple but ingenious solution to the the problem of having to support both 78 Rpm. and microgroove records on the same device, but on the end of the centelever you have not one but 2 stylii mounted opposite each other, one cut for an 18µm profile and another for a 63µm and a mechanism that allows you to turn the cantelever 180 degrees (somtimes the generator as well) when you wanted to use one fomat instead of the other. Early units featured a spring loaded knob on the front of the pickup you that you pulled out and turned, this mechanism was too heavy for the pickup and made the whole structure less rigid and thus fell out of use fairly quickly as the simpler method of having a plastic strip attached to the cantilever that you flipped from one side to side using your finger, this is still not a ideal solution since it is less rigid that a normal stylus but an acceptable compromise.

A Killick stylus profile
A type of a conical stylus where the tip is ground flat so that it has 2 contact points rather than 3, named after inventor Marie Louise Killick and was only used for a short while, most companies had dropped it as early as 1953.

The stylus lifetime
A budget shappire sylus supplied as a generic replacement is expected to last 400 to 500 hours, although your milage may vary. An industrial grade diamond like you see from the bigger suppliers will last 1000 hours, again, give or take, but this is by far the most common type of stylus. A very good, natural, crystal-oriented or grain oriented polished diamond that is used in high end moving coil pickups has a life of around 2500 to 3000 hours, and inferior such have a lifetime of around 2000 hours. You can half any lifetime expectation if you are using the pickup for DJ or broadcast use.

Technical Info.


The theory of RIAA EQ
In German but mostly math and drawings so should be understandable by most.

Turntable geometry
Has a few old (but very good) technical papers on turntable, arm and cart theory including the classic H. G. Bęrwald and Bauer papers..

Tweaking your record player
A old artice from 1990 written by J Gordon Holt and published by Stereophile, bit outdated but excellent info nonetheless..

Understanding The Issues Behind Cartridge Alignment
Article by Gary Markowitz that covers most of the basics.

Why Ortofon and Why moving Coil ?
This article is a bit out of date but it was originally written in the early 90's by the late Tony Sanderson, but it touches on some of the issues regarding pickups that come up from time to time esp. here in England, there is always the chant "MM is technically better" to be heard from the monster raving loony linn/naim crowd..

Calibration gear etc.


Asthetics
Makes Cartridge demagnetisers

Winds
Makes an high quality arm load meter.

Turntable Basics
Sell turntable accessories, calibration, belts etc..

Gyrascope
A fascinating, highly accurate and expensive turntable speed tester.

Van Den Hul
Makes a variety of turntable, tonearm and pickup calibration accessories.

Next Page : Pickups

© 1993 - 2013 Ólafur Gunnlaugsson, all rights reserved.


The site was last compiled on Sun Nov 10 2013 at 9:15:00am